Heretofore, there have widely been known a technology for forming a grinding tooth surface of a grinding tool by synchronously rotating the grinding tool and a dresser gear while the grinding tooth surface of the grinding tool and a dresser tooth surface of the dresser gear are being held in contact with each other, and a technology for grinding a tooth surface of a workpiece gear by synchronously rotating a grinding tool and the workpiece gear while a grinding tooth surface of the grinding tool and the tooth surface of the workpiece gear are being held in contact with each other.
In the technical field of the former technology, Japanese Patent No. 3679184 discloses a meshing method for accurately bringing the dresser tooth of the dresser gear and the grinding tooth of the grinding tool before the grinding tooth surface is formed.
Japanese Patent No. 3679184 states that a pulse generator generates pulses corresponding to an angular displacement of a grinding wheel drive motor. Based on a change in pulses output from the pulse generator, contact between a tooth surface of a tooth of a dresser and a grinding wheel is detected with respect to each of normal and reverse directions in which the grinding wheel rotates. The central position where the tooth of the dresser and the grinding wheel mesh with each other is determined from the detected contact.
In the technical field of the latter technology, Japanese Patent No. 3910427 and Japanese Laid-Open Patent Publication No. 2000-326141 disclose meshing methods which are relevant to the above meshing method.
Japanese Patent No. 3910427 states that based on a positional deviation of a workpiece shaft with respect to a command value for the workpiece shaft or a tool shaft, the position where a tooth surface of a tooth of a workpiece and a grinding surface of a grinding tool is detected with respect to each of normal and reverse directions in which the workpiece shaft rotates, and the central position where the tooth of the workpiece and the grinding surface of the grinding tool mesh with each other is determined from the detected position.
Japanese Laid-Open Patent Publication No. 2000-326141 states that contact between a tooth surface of a tooth of a gear to be machined and a side surface of a grinding wheel screw is confirmed by an acoustic emission (AE) ultrasonic sensor, and the central position where the tooth of the gear to be machined and the grinding wheel screw mesh with each other is determined from the detected contact.